Technical Abstract:
17ß-estradiol (E2) can induce endocrine disruptions at low concentrations. Laboratory studies have indicated low potential for persistence and mobility of E2 in the environment, and yet field studies measure estrogens at concentrations of concern. Humans and animals eliminate E2 primarily as a conjugate, which is more water soluble than the parent compound. In this study, the radiolabeled conjugate, [14C]E2-17sulfate (E2-17S), was investigated in batch studies to identify the processes controlling its dissipation in soils. E2-17S was added to two soils with different organic carbon contents (1.5 and 0.5%) which were either maintained as sterile or natural. Aqueous radioactivity in the batch experiments was measured through time, and HPLC was used to determine what metabolic events occurred for E2-17S. For the natural soils with high and low organic carbon content, 12% and 30%, respectively, of total radioactivity remained in the aqueous phase after 14 days. Aqueous radioactivity after 14 d in the sterile soils was 23% and 46% for the high and low organic carbon contents, respectively. The parent, E2-17S, was relatively stable in the aqueous phase for both natural and sterile soils. Hydroxylated metabolites of E2-17S but no hydrolyzed E2 was detected in the aqueous phase under both sterile and natural conditions. However, E2 and estrone were found in acetone extracts of the natural and sterile soils, which suggested that E2-17S could be deconjugation on soil surface. This study implies E2-17S could be a potential source of free estrogens in the environment.